Keywords

Abstract

A new mite species belonging to the genus Tegonotus Nalepa (Eriophyidae, Phyllocoptinae, Tegonotini), Tegonotus canaris n. sp. Xu, Chen, Xue, from Fuzhou, Fujian Province, southeastern China, is described and illustrated. This new species causes discoloured buds, curled leaf edges and necrosis on its host plant, Canarium album (Lour.) DC. (Chinese white olive) (Burseraceae). The character of divided empodium observed in this new species is presented for the first time in the genus Tegonotus.

Introduction

Chinese white olive, Canarium album (Lour.) DC. (Burseraceae), commonly called gan lan, "qing guo" in China, is indigenous to the southeast area of China (Fujian, Guangdong and Yunnan Provinces and Guangxi Autonomous Region) (Wei et al. 1999). Wild Chinese white olive tree is up to 25-35 meters tall, having a wide range of adaptability, e.g. sustainable at low temperatures (6 – 7°C) in winter, high temperatures (almost 40°C) in summer and poor soils and rocky hillsides (He and Xia 2007). Its fruits often used in Chinese folk medicine can be eaten raw, cooked or dried (Zhang et al. 2009) and are quite similar to the Mediterranean olive (Olea europaea L.) in the shape (fusiform), anatomy and taste (strong bitter and astringent), but mainly different at low oil contents (He et al. 2009). Nowadays this plant is widely cultivated in Fujian and Guangdong Provinces (e.g. more than 10 thousand hm2 in Fujian Province, Chen et al. 2011). Due to its diversified economy values, Chinese white olive has been introduced and extensively cultivated in other Asian tropical and semi-tropical countries (e.g. Vietnam, Malaysia and Japan) (Wei et al. 1999). During field surveys in 2011, an eriophyoid mite species was found infesting Chinese white olive and recently determined to be new to science belonging to the genus Tegonotus Nalepa (Phyllocoptinae, Tegonotini). This new eriophyoid mite species mainly affects the twigs with serious damage occurring in spring and autumn. At first, the buds and new growths become reddish (Fig. 1E). Then the edges of tender and young leaves curl and darken (Fig. 1A, 1B). Hereafter, the entire twigs turn brown and dry (Fig. 1C, 1D). For a long time the local people believed the symptoms were caused by a plant disease and sprayed fungicide to try control it, but failed. At present, no effective control measures are known for this new eriophyoid mite species.

Figure 1. Symptoms caused by Tegonotus canarisn. sp.: A-B – twigs with leaf edges curved and darkened; C-D – twigs brown and dry; E – bud discoloured red; F – healthy bud and leaves.
To date, the host plant genus Canarium includes 88 accepted taxa (The Plant List 2013) of median to large-sized canopy trees, distributed in tropical and subtropical regions of Africa, Asia, and Oceania (Weeks 2009). Based on published records in the literature, only five eriophyoid species have so far been reported infesting Canarium spp. (Table 1). Herein, a new eriophyoid mites of the genus Tegonotus is reported for the first from host plant genus Canarium and from family Burseraceae. The character of divided empodium observed in the new species is presented for the first in the genus Tegonotus and the tribe Tegonotini. A key to eriophyoid mites associated with Canarium spp. is provided.

Table 1. Eriophyoid mites associated with Canarium plants.

Materials and methods

Eriophyoid specimens collected from plant material were prepared and slide mounted according to the methods of Amrine and Manson (1996). Slides were mounted in a modified Berlese medium without adding additional fibers. The morphological terminology used herein follows Lindquist (1996), internal female genitalia nomenclature follows Chetverikov (2014) and the generic classification is made according to Amrine et al. (2003). Specimens were measured following de Lillo et al. (2010). They were examined with the aid of a Zeiss A2 (Germany) research microscope with phase contrast and semi-schematic drawings were made. Micrographs were taken with a Zeiss A2 (microphoto camera AxioCam MRc) research microscope with phase contrast using 10× eyepieces at 100× oil magnification, connected to a computer using Axiovision image analysis software. For each species the holotype female measurement precedes the corresponding range for paratypes (given in parentheses). For males, only range measurements are given. All measurements are in micrometers (μm) and are lengths when not otherwise specified.

Diagnosis — Tegonotus canarisn. sp. differs from all the other Tegonotus species in having divided empodium; prodorsal shield with a depressed hollows pattern: four hollows present at basal 2/3, one bottle-like hollow and four open hollows present at basal 1/3, some additional open hollows present at anterior and lateral margins; opisthosoma with irregular, broad and “thickening” dorsal annuli, a slight and irregular dorsal ridge maybe present, all dorsal annuli with lateral projections except posterior 3 to 4 annuli, lateral view of dorsal annuli with irregular "fissures".

Type material — Holotype, female, found on Canarium album (Lour.) DC. (Burseraceae), Institute of Pomology, Fujian Academy of Agricultural Science, Fuzhou City, Fujian Province, People’s Republic of China, 31 December 2011, coll. Jin Chen and Xing-Quan Xu, deposited as a slide-mounted specimen in the Arthropod/Mite Collection of the Department of Entomology, NJAU, Jiangsu Province, China. Paratypes, 14 females and 6 males on seven slides, from C. album (Lour.) DC. (Burseraceae), same details as holotype, deposited as a slide mounted specimen in the Arthropod/Mite Collection of the Department of Entomology, NJAU, Jiangsu Province, China. Six females on two slides, from C. album (Lour.) DC. (Burseraceae), same details as holotype, deposited as a slide mounted specimen in NZMC, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.

Relation to plant host — Vagrant on the under leaf surface, causing leaf edges to become curved, later becoming dark, dry and defoliated; causing bud to discoloured red.

Etymology — This species designation canaris is derived from the generic name of the host plant, Canarium, by adding the postfix. The gender is neuter.

The subfamily Phyllocoptinae includes five tribes: Acaricalini, Anthocoptini, Calacarini, Phyllocoptini and Tegonotini (Amrine et al. 2003). Following the key of Amrine et al. (2003), the tribe Tegonotini can be differentiated from others in the Phyllocoptinae by characters as: empodium entire, scapular setae present, dorsal annuli with lateral lobes or projections. The morphological character of empodium is widely used in the classification of eriophyoid mites at generic, tribal or subfamilial level (Amrine, 2003). Basically there are two types of empodium in eriophyoid mites, divided or simple. Following the key of Amrine et al. (2003), T. canarisn. sp. should certainly be put into the subfamily Phyllocoptinae, while the status at tribal level was unclear (P57, Amrine 2003). The tribe Acaricalini has an obligatory character of empodium, divided. Based on the molecular phylogenetic analysis, monophyly of Acaricalini was rejected (Li et al. 2014). Empodium divided as a proposed synapomorphy of Acaricalini was also rejected by Li et al. (2014). Herein, divided empodium was not considered as a synapomorphic character of Acaricalini. Besides character of empodium, T. canarisn. sp. should belong to the tribe Tegonotini as having scapular setae present (Figures 3-6) and opisthosoma with projections from some annuli (Figure 2). We first describe one Tegonotus species in the tribe Tegonotini having divided empodium. The character of divided empodium was also found in Notostrix spp. in the tribe Anthocoptini of Phyllocoptinae. Apically divided empodium was found in N. jamaicae (Keifer 1970). Bipartite empodium was found in N. fissipes (Navia and Flechtmann 2003). Furthermore, tripartite empodium was found in N. exigua (Flechtmann 1998), N. trifida and N. miniseta (Navia and Flechtmann 2003).

Acknowledgements

This research was funded by the National Natural Science Foundation of China (No. 31672337). We thank Dr. Charnie Craemer (ARC-Plant Protection Research Institute), Dr. Riaan Stals (ARC-Plant Protection Research Institute), Dr. Enrico de Lillo (University of Bari Aldo Moro), Prof. James W. Amrine (West Virginia University) and one anonymous reviewer for their invaluable comments. Especially, we thank Dr. Denise Navia (Embrapa Genetic Resources and Biotechnology) for her critical comments and processing our manuscript.